A new way to look at side effects of first-line prostate cancer treatment

Academic research into the side effects of different treatments for localized prostate cancer have long been hampered by the lack of consistently used criteria for the assessment of those side effects at baseline and at defined time-periods post-treatment.

There are two new methods that have recently been developed specifically for use in prospective studies of adverse effects after treatment:

  • The proportion of patients regaining 90 percent of baseline function after a specific procedure (PBS-90) — which can be used to assess when recovery from a side effect of treatment will have stabilized
  • The generalized estimating equation (GEE) — which can be used to estimate the time points at which a final outcome can be expected

Stensvold et al. report using both of these new tools prospectively to examine changes of sexual, urinary, and bowel functions after either robot-assisted prostatectomy (RALP) or conformal external beam radiotherapy (EBRT) in men with localized prostate cancer, treated without any recourse to neoadjuvant or adjuvant androgen deprivation therapy (ADT).

All patients were asked to complete the UCLA Prostate Cancer Index (UCLA-PCI) questionnaire at baseline and at 3, 6, 12, and 24 months post-treatment.

  • 254 patients were included in this prospective study.
    • 150 men (59.1 percent) were treated with RALP.
    • 104 men (49.9 percent) were treated with EBRT.
  • At 24 months post-treatment, PBS-90 levels for men treated with RALP were
    • 34 percent for urinary function
    • 7 percent for sexual function
    • 86 percent for bowel function
  • Also at 24 months post-treatment, PBS-90 levels for men given EBRT were
    • 69 percent for urinary function
    • 70 percent for sexual function
    • 70 percent for bowel function
  • GEE analysis showed that the function scores at 6 months were significantly associated with the functions at 24 months.
  • PBS-90 showed that stability of function was reached at 3 months for urinary function and at 6 months for sexual and bowel functions.

Now it might be a mistake to assume from these data that all men receiving RALP would inevitably have side effects this bad compared to EBRT. We have no idea of the skill levels of the surgeons doing RALP in this study. What we need is to see data from other patient series that use the same set of tools in the same way to assess the side effects of these two types of treatment. However, it is very clear that — in these two cohorts of patients — the complications associated with RALP at 2 years post-treatment were notably worse that those associated with EBRT.

Whether consistent use of PBS-90 and GEE in association with the UCLA-PCI or some other questionnaire can help to offer a “standardized” method for assessment of adverse effects following first-line treatment for prostate cancer will take a while to resolve.

3 Responses

  1. This is a stunning difference in QoL outcomes between EBRT and RALP. At a minimum, one would have expected RALP to clearly outperform EBRT in bowel function, since RT impinges on the bowels far more. (RALP does score more highly but not overwhelmingly so.) EBRT usually edges out RALP in urinary and sexual function, especially when IMRT and other more precise forms of RT are employed. Highly significant to me in the EBRT data is that this snapshot is taken at 24 months post-treatment. Since RT can damage adjacent healthy tissue, and since such collateral damage can take time to materialize (typically 18-24 months), these EBRT results strike me as even more impressive due to the fact that they do contemplate the typical lag in impacts.

    This is a good study for the EBRT crowd. Nevertheless, as the moderator noted, we don’t know what kind of a surgeon was performing all those RALPs. I have to suspect that if a Johns Hopkins or MSKCC surgeon were at the helm, the RALP outcomes would have almost surely been more favorable.

  2. How do you measure “90 percent of baseline function”? What is 90% continence? What is a 90% erection? Is that with or without Viagra?

  3. Richard:

    That’s the whole point. It doesn’t matter how you measure them using this system. What matters is only the relative value (10%, 25%, 90%) compared to the baseline value before treatment. How they were assessed in this case is shown on the actual UCLA PCI form linked to in the text above.

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